Unify command help so that help options do not begin with "--" in command help.

The 'options' array for newer commands, like drupal-directory and site-install, list their options without a preceding "--", whereas older commands such as help do.

For example:

  $items['help'] = array(
    'description' => 'Print this help message. See `drush help help` for more options.',
    'bootstrap' => DRUSH_BOOTSTRAP_DRUSH, // No bootstrap.
    'options' => array(
      '--sort' => 'Sort commands in alphabetical order. drush waits for full bootstrap before printing any commands when this option is used.',
      '--filter' => 'Restrict command list to those commands defined in the specified file.',
      '--html' => 'Print help for all commands in HTML format.',
      '--pipe' => 'A list of available commands, one per line.',
    ),

... and:

  $items['site-install'] = array(
    'description' => 'Install Drupal along with modules/themes/configuration using the specified install profile.',
    'arguments' => array(
      'profile' => 'the install profile you wish to run. defaults to \'default\'',
    ),
    'options' => array(
      'db-url' => 'A Drupal 5/6 style database URL. Only required for initial install - not re-install.',
      'db-prefix' => 'An optional table prefix to use for initial install.',
      'account-name' => 'uid1 name. defaults to admin',
      'account-pass' => 'uid1 pass. defaults to admin',
      'account-mail' => 'uid1 email. defaults to admin@example.com',
      'locale' => 'A short language code. Sets the default site language. Language files must already be present. You may use download command to get them.',
      'clean-url'=> 'Defaults to 1',
      'site-name' => 'Defaults to Site-Install',
      'site-mail' => 'From: for system mailings. Defaults to admin@example.com',
      'sites-subdir' => "Name of directory under 'sites' which should be created. Only needed when the subdirectory does not already exist. Defaults to 'default'",
    ),

Seems this should be standardized one way or the other. I would tend to think that the newer way, without the "--", is better. If you like the way that 'help' renders it better with the "--", then maybe help could automatically prepend -- to each help item?

Options could also be exploded on "," and prepended with just a "-" if the option was but a single character. This would be a good first step toward #996092: Better handling of unknown option. Alternately, we could leave the global options as they are.

At a minimum, though, the options should be standardized one way or the other.